The eye is a complex organ with unique anatomy and physiology. The structure of the eye can be divided into two parts, the anterior and posterior. The cornea, conjunctiva, aqueous humor, iris, ciliary body and lens are in the anterior portion. The posterior portion includes the sclera, choroid, retinal pigment epithelium, neural retina, optic nerve and vitreous humor. The most important diseases affecting the anterior segment include glaucoma, allergic conjunctivitis, anterior uveitis and cataracts. The most prevalent diseases affecting the posterior segment of the eye are dry and wet age-related macular degeneration (AMD) and diabetic retinopathy.
Typical routes of drug delivery to the eye are topical, systemic, subconjunctival, intravitreal, puntal, intrasceral, transscleral, anterior or posterior sub-Tenon's, suprachoroidal, choroidal, subchoroidal, and subretinal.
To address issues of ocular delivery, a large number of types of delivery systems have been devised. Such include conventional (solution, suspension, emulsion, ointment, inserts and gels); vesicular (liposomes, exosomes, niosomes, discomes and pharmacosomes), advanced materials (scleral plugs, gene delivery, siRNA and stem cells); and controlled release systems (implants, hydrogels, dendrimers, iontophoresis, collagen shields, polymeric solutions, therapeutic contact lenses, cyclodextrin carriers, microneedles and microemulsions and particulates (microparticles and nanoparticles)).
Topical drops are the most widely used non-invasive routes of drug administration to treat anterior ocular diseases. However, a number of barriers exist to effective topical delivery, including tear turnover, nasolacrimal drainage, reflex blinking, and the barrier of the mucosal membrane. It is considered that less than 5% of topically applied dosages reach the deeper ocular tissue.
The patient may be required to instill topical drops up to four times a day. Indeed, certain patients, including corneal transplant recipients, require therapeutic doses of medications to be continuously maintained in the corneal tissues and some patients are required to endure lengthy and arduous dosing regimens that often involve up to hourly application. Each repeat dosing not only requires a further investment of a patient's time, but also increases the chance of irritation and non-compliance.
Drug delivery to the posterior area of the eye usually requires a different mode of administration from topical drops, and is typically achieved via an intravitreal injection, periocular injection or systemic administration. Systemic administration is not preferred given the ratio of volume of the eye to the entire body and thus unnecessary potential systemic toxicity. Therefore, intravitreal injections are currently the most common form of drug administration for posterior disorders. However, intravitreal injections also risk problems due to the common side effect of inflammation to the eye caused by administration of foreign material to this sensitive area, endophthalmitis, hemorrhage, retinal detachment and poor patient compliance.
Transscleral delivery with periocular administration is seen as an alternative to intravitreal injections, however, ocular barriers such as the sclera, choroid, retinal pigment epithelium, lymphatic flow and general blood flow compromise efficacy.
To treat ocular diseases, and in particular disease of the posterior chamber, the drug must be delivered in an amount and for a duration to achieve efficacy. This seemingly straightforward goal is difficult to achieve in practice.
Examples of common drug classes used for ocular disorders include: prostaglandins, carbonic anhydrase inhibitors, receptor tyrosine kinase inhibitors (RTKIs), beta-blockers, alpha-adrenergic agonists, parasympathomimetics, epinephrine, and hyperosmotic agents.
Although a number of prostaglandin carboxylic acids are effective in treating eye disorders, for example, lowering intraocular pressure (IOP), their hydrophilic nature can lead to rapid clearance from the surface of the eye before effective therapy can be achieved. As a result, prostaglandins are dosed in the form of selected esters to allow entry to the eye and a “prolonged” residence. When in the eye, native esterase enzymes cleave the prostaglandin ester to release the active species. Despite this innovation, current drop administered prostaglandins, for example, latanoprost, bimatoprost, and travoprost, still require daily or several times daily dosing regimens and may cause irritation or hyperemia to the eye in some patients. In addition, nearly half of patients on prostaglandin therapy for glaucoma require a second agent for control of IOP (Physician Drug and Diagnosis Audit (PDDA) from Verispan, L.L.C. January-June, 2003)
Carbonic anhydrase inhibitors (CAIS) are used as an alternative and sometimes in conjunction with prostaglandins to treat eye disorders. Unfortunately, compliancy issues can occur as these medications also require daily or dosing up to four times a day, and may also cause irritation or hyperemia to the eye in some patients.
Another potential avenue for the treatment of ocular disorders involves protecting neurons directly. Preliminary data on receptor tyrosine kinase inhibitors (RTKIs) and dual leucine zipper kinase inhibitors (DLKIs) suggests that instead of treating increasing ocular pressure, molecules such as Sunitinib and Crizotinib can prevent the nerve damage that is associated with it. Unfortunately, Sunitinib has had observed hepatotoxicity in both clinical trials and post-marketing clinical use.
References that describe treatments of ocular disorders and the synthesis of compounds related to treating ocular disorders include the following: Ongini et al., U.S. Pat. No. 8,058,467 titled “Prostaglandin derivatives”; Qlt Plug Delivery Inc, WO2009/035565 titled “Prostaglandin analogues for implant devices and methods”; Allergan Inc, U.S. Pat. No. 5,446,041 titled “Intraocular pressure reducing 11-acyl prostaglandins”; Upjohn Co., DE2263393 titled “9-O-Acylated prostaglandins F2a”; Shionogi & Co. patent publication 948,179 titled “Treatment for hypertension or glaucoma in eyes”; Ragactive, EP1329453 titled “Method for obtaining 4-(n-alkylamine)-5,6-dihydro-4h-thieno-(2,3-b)-thiopyran-2-sulfonamide-7,7-dioxides and intermediate products”; and American Cyanamid Co. GB844946 titled “2-(N-Substituted)acylamino-1,3,4-thiadiazole-5-sulfonamides”.
Other publications include Vallikivi, I., et al. (2005). “The modelling and kinetic investigation of the lipase-catalyzed acetylation of stereoisomeric prostaglandins.” J. Mol. Catal. B: Enzym. 35(1-3): 62-69; Parve, O., et al. (1999). “Lipase-catalyzed acylation of prostanoids.” Bioorg. Med. Chem. Lett. 9(13): 1853-1858; and Carmely, S., et al. (1980). and “New prostaglandin (PGF) derivatives from the soft coral Lobophyton depressum.” Tetrahedron Lett. 21(9): 875-878.
Patent applications that describe DLK inhibitors include: Zhejiang DTRM Biopharma Co., patent publication WO2014146486 titled “Three-level cyclic amine ALK kinase inhibitor for treating cancer”; Kyowa Hakko Kogyo Co., patent publication WO2005012257 titled “Indazole Derivatives”; Genetech, patent publication WO2014177524 titled “C-linked heterocycloalkyl substituted pyrimidines and their uses”, and patent publication WO2013174780 titled “Substituted dipyridylamines and uses thereof”.
Patent applications that describe derivatives of prostaglandins include: Allergan, U.S. Pat. No. 5,767,154 titled “5-tran-prostaglandins of the F series and their use as ocular hypotensives”, U.S. Pat. No. 5,767,154 titled “5-trans-prostaglandins of the F series and their use as ocular hypotensives”; Alcon Laboratories, EP0667160A2 titled “Use of certain prostaglandin analogues to treat glaucoma and ocular hypertension”, EP667160 titled “Use of certain prostaglandin analogues to treat glaucoma and ocular hypertension; Asahi glass company and Santen Pharmaceutical Co., EP0850926A2 titled “Difluoroprostaglandin derivatives and their use”; Asahi Glass Co., JP2000080075 titled “Preparation of 15-deoxy-15,15-difluoroprostaglandins as selective and chemically-stable drugs”, JP11255740 titled “Preparation of 15-deoxy-15-monofluoroprostaglandin derivatives”, JP10087607 titled “Preparation of fluorine-containing prostaglandins as agents for inducing labor and controlling animal sexual cycle”, WO9812175 titled “Preparation of fluorinated prostaglandin derivatives for treatment of glaucoma”; Santen Pharmaceutical Co., JP10259179 titled “Preparation of multi-substituted aryloxy-group containing prostaglandins and their use”, EP850926 titled “Preparation of difluoroprostaglandin derivatives and their use for treatment of an eye disease”;
The object of this invention is to provide improved compounds, compositions and methods to treat ocular disorders.